The homes, which he may be planning to combine, total $22.078 million

Hedge fund billionaire Bill Ackman is buying up the Beresford, an iconic luxury co-op on the Upper West Side with celebrity residents past and present including Diane Sawyer, Brian Williams and Jerry Seinfeld.

Over the past three months, Mr. Ackman has bought two units on the eighth floor of the pre-war building for a combined $22.078 million, according to property records. The fund manager who founded Pershing Square Capital Management bought the apartments to be closer to his three children, who live at the Beresford in a unit Mr. Ackman used to share with his ex-wife, Mansion Global has learned.

He bought one of the co-ops in June for $8.578 million in an off-market deal with few details. A month before that, he sealed the deal on a neighboring three-bedroom, three-bathroom for $13.5 million, records show. Luxury Listings NYC was the first to report the purchases.

Despite the steeper price tag, Mr. Ackman appeared to get a deal on the more expensive unit. It was on the market as recently as October for nearly $19 million, but Mr. Ackman snagged it for a 29% discount, listing records show.

The 51-year-old fund manager, whose wealth Forbes pegs at about $1.4 billion, used to live with his ex-wife, Karen Herskovitz, in a lavish duplex on the 17th and 18th floors. He and Ms. Herskovitz bought the home overlooking Central Park West for $26 million in 2006, according to property records.

There’s little public information available about Mr. Ackman’s nearly $8.6 million purchase, but the $13.5 million unit comes with views all the way down Central Park, according to an old listing with Fox Residential Group. The home has hardwood floors, a gas fireplace in the dining room and venetian plaster walls that camouflage hidden storage space.